Researchers at the University of California, Davis are investigating the nanoscopic structure and non-adhesive property of polyethylene glycol (PEG) hydrogel, which enables remarkable, high-selectivity nanoassembly.

The team uses microfabricated PEG hydrogel templates of 500 nm and 1 µm resolution to assist the self assembly of functional nanocolloids through a controlled evaporative approach. As shown in the SEM photographs of the pattern-assisted assembly (PAN), simply varying the concentration of colloidal particles in aqueous suspension can lead to different morphologies of nanocolloid arrays in the PEG nanostructures, which is of potential use in photonic crystal and biosensing applications.

The traditional way of preventing assembled colloids from adhering to the surface, is through the control of surface hydrophobicity or wettability. In this study, the PEG hydrogel nanosurfaces exhibit both superhydrophilicity and high wettability (contact angle of 22º). Therefore, unlike the traditional patterned wettability technique, the pattern-assisted assembly process takes advantage of the unique non-adhesive (or non-fouling) property of PEG hydrogels to achieve the highly selective nanoassembly.

As one of the best known biomaterials with an extremely low surface energy, the non-adhesive property of the PEG hydrogel is attributed to its high surface resistance to non-specific adsorption, which is crucial to prevent the nanocolloids from sticking to the surface during the nanoassembly process.

The group presented its work in Nanotechnology.